Apparatus and Method

ABSTRACT

The present invention provides an apparatus ( 10 ) and method for transmitting torque to a downhole device. The apparatus ( 10 ) comprises a first part and a second part adapted for connection to the downhole device. The apparatus ( 10 ) also comprises an engagement means ( 100, 120 ). The first and second parts are connected together such that relative axial movement between the first and second parts is constrained on a helical path. The engagement means ( 100, 120 ) are arranged to rotationally connect the first and second parts to thereby transmit torque from the first part to the second part when a coupling point is reached on the helical path.

The present invention relates to apparatus and a method for transmitting torque to a downhole device. In particular, the invention relates to a tool that can be removably attached to e.g. a wireline string at one end and coupled to a target downhole device, such as a tubing hangar plug, at the other end. Actuation of the tool transmits torque to the attached device.

Wireline apparatus is widely used in the oil and gas industries to suspend a string of tools in a cased wellbore. Typically, devices run downhole on a wireline string cannot easily be rotated, as the only connection between the topsides end of the wireline and the tool string is the flexible cable. If rotation of the device is required, one conventional way of achieving this is to run a drillstring downhole with the attached tool, which necessitates use of a rig.

According to a first aspect of the invention, there is provided apparatus for transmitting torque to a downhole device, the apparatus comprising a first part, a second part adapted for connection to the downhole device and an engagement means, wherein the first and second parts are connected together such that relative axial movement between the first and second parts is constrained on a helical path, and wherein the engagement means are arranged to rotationally connect the first and second parts to thereby transmit torque from the first part to the second part when a coupling point is reached on the helical path.

Preferably the first and second parts of the apparatus are axially aligned. The first part can be provided with a throughbore and a portion of the second part is arranged to be selectively movable in the throughbore of the first part.

The first part can move axial along the helical path and so pick up rotational momentum as it proceeds on the path. Before the coupling point is reached on the path the rotational momentum of the first part is preserved within the first part. On reaching the coupling point, the engagement means rotationally connect the two parts and the rotational momentum stored in the first part is then transmitted to the second part, and thence to the downhole device.

The engagement means can comprise a clutch having first and second mating portions, and wherein a first portion of the clutch is connected to the first part and a second portion of the clutch is connected to the second part.

Mating threads can be provided on the first and second parts to restrain relative movement therebetween to the helical path. A bearing can be provided between the first and second parts. The bearing can be a ball bearing or a roller bearing. Preferably, the first and second parts can be connected by means of a ball screw assembly.

By virtue of the connection between the first and second parts, the first part can travel relative to the second part, accelerating under gravity, until the clutch mechanism engages at the coupling point. The coupling point can typically be at the end of the helical path, but this is not necessary.

The second part can include a connector for removable attachment to the downhole device, such that torque is transmitted and rotational movement of the second part causes rotational movement of the connector. When a downhole device is attached to the apparatus by means of the connector, the impact torque at the coupling point can be used to rotate the downhole device via the connector.

Thus the apparatus can be used to transmit torque to a downhole device. The apparatus is useful for any application where rotation of a portion of a wireline string is required. This has the advantage that use of expensive and complex topsides equipment to supply the rotational force can be circumvented.

The first part can include a housing. The first part can be provided with a linear displacement means, the linear displacement means comprising a shaft and a spring, such that the spring is biased to restrict relative movement of the shaft and the housing.

In the case where the second part comprises a lead screw, the lead screw is preferably axially aligned with the shaft, such that on actuation of the linear displacement means the shaft moves in an axial direction against the lead screw. Contact between the lead screw and the shaft of the linear displacement means can cause a jarring action.

According to a second aspect of the present invention, there is provided a method of imparting torque to a downhole device including the steps:

-   -   providing a first part, a second part and engagement means;     -   restraining relative movement of the first part and the second         part on a helical path;     -   transmitting torque from the first part to the second part on         engagement of the engagement means.

The method can comprise the step of engaging the first part and second part by providing a first portion of a clutch on the first part and a second portion of the clutch on the second part.

The method can include the step of providing a throughbore in a portion of the first part and selectively moving a portion of the second part within the throughbore of the first part.

The method can include the step of suspending the first part from wireline and allowing the second part to move under gravity relative to the first part.

The method can include the step of preventing axial movement beyond a first position of the second part relative to the first part.

The method can include releasing the wireline suspension thereby allowing the first part to move axially relative to the second part. Slacking off the wireline can initiate rotation.

The method can include providing linear displacement means in the first part and axially aligning the linear displacement means with the second part. Moving the linear displacement means in an axial direction can jar the second part. In the event that a restriction is encountered, the jarring action is useful to enable the restriction to be bypassed.

One embodiment of the invention will now be described with reference to and as shown in the accompanying drawings, in which:

FIG. 1 is a perspective view of a torque tool in accordance with the present invention;

FIG. 2 is a sectional view of the end portions of the torque tool of FIG. 1;

FIGS. 3( a) to 3(e) are sectional views, which together show the torque tool of FIG. 2 in greater detail;

FIG. 4 is a sectional elevation along the line B-B shown in FIG. 3( a);

FIG. 5 is a sectional elevation along the line C-C shown in FIG. 3( b);

FIG. 6 is a sectional elevation along the line D-D shown in FIG. 3( b);

FIG. 7 is a sectional elevation along the line E-E shown in FIG. 3( c);

FIG. 8 is a side view of the portion J-J shown in FIG. 3( c);

FIG. 9 is a sectional elevation along the line F-F shown in FIG. 3( c);

FIG. 10 is a sectional elevation along the line G-G shown in FIG. 3( c);

FIG. 11 is a sectional elevation along the line H-H shown in FIG. 3( d);

FIG. 12 is a perspective view of an upper clutch of the FIG. 1 tool;

FIG. 13 is a sectional view of the upper clutch shown in FIG. 12;

FIG. 14 is a perspective view of a lower clutch of the FIG. 1 tool; and

FIG. 15 is a sectional view of the lower clutch shown in FIG. 14.

FIGS. 1 and 2 show a torque tool in accordance with the present invention and indicated generally at 10. The torque tool 10 comprises a top sub 12, an upper crossover 50, an outer tubing 70, an upper clutch 100, a lower clutch 120, a lower crossover 130, a retaining ring 134 and a fluted prong 90.

The torque tool is arranged in two basic parts. The first part comprises the top sub 12, the upper crossover 50, the outer tubing 70, and the upper clutch 100. The second part comprises the lower clutch 120, the lower crossover 130, and the fluted prong 90. The second part can move axially within the bore of the first part.

The top sub 12, shown in more detail in FIG. 3 a, has a connector 14 at one end thereof, defining an upper end of the torque tool 10. The top sub 12 is also provided with a neck 220, an upwardly projecting shoulder portion 222 and a substantially cylindrical waisted body portion 16. An annular step 19 is provided at the point where the shoulder portion 222 meets the waisted body portion 16, facing the lower end of the top sub 12.

The upper crossover 50 is substantially cylindrical and is provided with an axial throughbore 48. The inner diameter of the throughbore 48 is greater than the outer diameter of the waisted body portion 16. An annular step 56 is provided facing towards the upper end of the upper crossover 50. The throughbore 48 of the upper crossover 50 has an inwardly projecting annular lip 54. At the lower end of the upper crossover 50 a pin connection 52 is provided.

The outer tubing 70 is substantially cylindrical and is provided with an axial throughbore 68. At the upper and lower ends of the outer tubing 70, box connections 72 a, 72 b are provided for connection to the upper crossover 50 and the upper clutch 100 respectively. The outer tubing 70 houses an end stop 60 and a ball screw assembly 80 in the throughbore 68. The ball screw assembly 80 comprises a lead screw 180 having a helical thread. A nut 182 is provided with a ball race (not shown), which cooperates with the helical thread of the lead screw 180. The nut 182 is rigidly connected to the outer tubing 70, and so forms another component of the first part. The lead screw 180 is rigidly connected (indirectly) to the prong 90, and thus forms another component of the second part. Standard ball screw assemblies are known to a person skilled in the art. The lower end of the lead screw 180 is provided with a pin connection 228.

The upper clutch 100 is shown in greater detail in FIGS. 12 and 13. The upper clutch 100 has a throughbore 106. At the upper end of the upper clutch 100, a pin end connection 102 is provided for connection to the box connection 72 b on the outer tubing. At its lower end, the upper clutch 100 is provided with two pairs of diametrically opposing teeth 104 protruding axially from its lower face. Each tooth 104 has one flat face 108 that extends parallel to the axis of the throughbore 106 and one angled face 109, which is milled at approximately 45° with respect to the axis.

The lower clutch 120 is shown in greater detail in FIGS. 14 and 15. The lower clutch 120 is provided with an axial throughbore 126 and a series of radial slots 118 extending through the side wall thereof. At the upper end, the lower clutch 120 has two pairs of diametrically opposing teeth 114. The teeth 114 each have a flat face 112 that extends parallel to the axis of the throughbore 126 and an angled face 113 as previously described for the upper clutch 100, but facing in the opposite axial direction. The angle on the faces 109 of the teeth 104 of the upper clutch 100 match the angle on the faces 113 of the teeth 114 of the lower clutch 120.

The lower end of the lower clutch 120 has castellations 116 extending axially therefrom. The radially outermost faces of the castellations 116 taper radially inwards at 117.

The lower crossover 130 is provided with a box connection 232 at its upper end and a box connection at its lower end 234 for connection to the lower clutch 120 and the fluted prong 90 respectively.

The upper end of the fluted prong 90 has a pin connection 190 and an outer portion of the fluted prong 90 has an annular V-shaped notch 98. Towards its lower end 92, the fluted prong 90 is provided with splined keys 94.

The tool 10 is assembled by inserting the waisted body portion 16 of the top sub 12 into the throughbore 48 of the upper crossover 50. Needle thrust bearings 30 are provided on either side of the annular lip 54. Prior to insertion into the throughbore 48, a lee spring 20 is provided around the body portion 16. The lee spring 20 is located between the step 19 and the upper needle thrust bearing 30. The top sub 12 is maintained in position by provision of two diametrically opposed socket head screws 122 as shown in FIG. 4. The two socket head screws 122 are located in recesses 18. An annular adjuster nut 40 is provided to hold the screws in position within the recesses 18.

The pin end connection 52 of upper crossover 50 is offered to the box end connection 72 a of the outer tubing 70. The upper crossover 50 and outer tubing 70 are secured together by two pairs of diametrically opposing socket head screws 122 as shown in FIG. 6, which extend through threaded apertures in the outer tubing 70.

The end stop 60 is located within the outer tubing 70. The end stop 60 is provided with a threaded lower central protrusion 62 that extends into a correspondingly threaded recess 84 provided in the lead screw 180. An outer diameter of the nut 182 is secured to an inner portion of the outer tubing 70 by means of a threaded connection 142 and an annular spacer washer 66 is provided at the point of connection. The lead screw 180 comprises a screw with a helical external groove, a nut 182 with an internal helical groove, and (optionally) a circuit of steel balls (not shown) bearing between the screw 180 and nut 182. The pitch of the threads can be adjusted to vary the rotational momentum required, as the first part will move more slowly (but with more of a rotational component) with a shallower pitch, and more quickly (but with a reduced rotational component) with a steeper pitch.

The outer tubing 70 is joined to the upper clutch 100 by mating of the pin end connection 102 and the box end connection 72 b. The portions are locked together by diametrically opposed socket head screws 74 extending through the box connection 72 b, as shown in FIG. 7.

At the lower end of the ball screw assembly 80 the pin connection 228 is mated to the box connection 232 of the lower crossover 130. The box connection 234 at the lower end of the lower crossover 130 receives the pin connection 190 at the upper end of the fluted prong 90. The lower end of the lower crossover 130 is axially aligned with the V-shaped notch 98 on the outer diameter of the fluted prong 90.

The lower clutch 120 is assembled over the lower crossover 130. Four socket head cap screws 122 are provided to secure the lower clutch 120 in position as shown in FIG. 9. The retainer ring 134 is assembled over the fluted prong 90 and temporarily secured in place using shear screws 136.

Before use, in the present embodiment the connector 14 at the upper end of the top sub 12 is attached to a wireline (not shown). The spline keys 94 on the end of the fluted prong 90 engage a portion of a tubing hangar plug (THP). Once assembled in the manner described above, the tool 10, attached wireline and THP are run into a wellbore as a single assembly.

During running of the tool 10 into the wellbore, gravity pulls the second part (and the attached THP) down relative to the first part, and thus the helical grooves between the lead screw 180 and the nut 182 cause the free helical rotation of the lead screw 180 through the (relatively stationary) nut 182 until the stop 60 positioned at the end of the lead screw 180 contacts an upper portion of the nut 182. At this point the second part has dropped about 1 metre relative to the first part, and the nut 182 is positioned at the top of the lead screw 180. Thus the first portion is held axially spaced above the second portion, ready for deployment.

When the THP first hits the hanger where it is to be set, the slight slackening of the wireline can be detected topsides, and the length of wire expended can be used to verify that the THP is in place in the hanger.

When rotation of the THP is required for final setting, rapid slacking off of tension in the wireline initiates free movement of the nut 182 and the whole of the first portion down the helical grooves of the lead screw 180. The first portion accelerates down the helical path under the weight of the relatively heavy outer components such as the upper clutch 100, the outer tubing 70, the upper crossover 50 and the top sub 12. As the first portion accelerates, it gains rotational momentum as it axially converges on the lower clutch 120. This convergence continues until the upper and lower clutches engage when the flat faces 108 of the teeth 104 of the upper clutch 100 abut the flat faces 112 of the teeth 114 of the lower clutch 120 as shown in FIG. 8. Shortly before the impact, the rotational momentum in the fast moving first portion is at its peak, but the whole momentum is stored within the first portion, and is not transmitted to the second portion. At the moment of impact, the clutches engage and the full momentum of the first portion is instantaneously transmitted to the second portion via the lower clutch. This rotational momentum is thus transmitted to the fluted prong 90, and thus to the attached THP, which is thereby set. If the THP is not fully set by the first impact, the tension can be taken up in the wireline, so that clutch disengages, the first portion moves back up the helical path to the top of the lead screw, and the first portion is dropped again, causing another impact and applying the same torque again to the THP. This can be done as often as necessary to ensure that the THP is properly set.

In the event that a restriction is encountered, the tool can be jarred. In this case, continued upward pull on the attached wireline will overcome the biasing force of the lee spring 20 thereby causing the lee spring 20 to extend. Once the wireline is suddenly slackened the lee spring 20 and attached top sub will recoil allowing axial movement of the waisted body potion 16 to impact against the stop 60. This causes a jarring action. The predetermined force required for the jarring can be altered by adjusting the strength of the lee spring 20 and tightening or slackening the adjustor nut 40.

The tool 10 is preferably able to operate around pressures of 3000 psi and between a temperature range of −21 to 163° C.

Modifications and improvements may be incorporated without departing from the scope of the present invention. For example the tool 10 can be used to transmit torque to any target device. While the above-described embodiment shows a tool that is attached to the downhole device before being run in to the hole, the tool could equally engage a target downhole device that is already in place in the hole. For example, the assembly could be lowered into the wellbore until it meets the downhole device to be rotated. At that point, the fluted prong can engage in a socket on the downhole device. 

1. Apparatus for transmitting torque to a downhole device, the apparatus comprising a first part, a second part adapted for connection to the downhole device and an engagement mechanism, wherein the first and second parts are connected together such that relative axial movement between the first and second parts is constrained on a helical path, and wherein the engagement mechanism is arranged to rotationally connect the first and second parts to thereby transmit torque from the first part to the second part when a coupling point is reached on the helical path.
 2. Apparatus as claimed in claim 1, wherein the first and second parts are axially aligned.
 3. Apparatus as claimed in claim 1, wherein the engagement mechanism comprises a clutch having first and second mating portions, and wherein a first portion of the clutch is connected to the first part and a second portion of the clutch is connected to the second part.
 4. Apparatus as claimed in claim 1, wherein the first part is provided with a throughbore and a portion of the second part is arranged to be selectively movable in the throughbore of the first part.
 5. Apparatus as claimed in claim 4, having mating threads on the first and second parts to restrain relative movement therebetween to the helical path.
 6. Apparatus as claimed in claim 1, wherein the second part includes a connector for removable attachment to the downhole device, such that rotational movement of the second part causes rotational movement of the connector.
 7. Apparatus as claimed in claim 1, having a bearing between the first and second parts.
 8. Apparatus as claimed in claim 1, wherein the first part is provided with a linear displacement device.
 9. Apparatus as claimed in claim 8, wherein the first part has a housing and the linear displacement device comprises a shaft and a spring, such that the spring is biased to restrict relative movement of the shaft and the housing.
 10. Apparatus as claimed in claim 9, wherein the second part is provided with a lead screw and the shaft is axially aligned with the lead screw, such that on actuation of the linear displacement device the shaft moves in an axial direction against the lead screw.
 11. A method of imparting torque to a downhole device including the steps: providing a first part, a second part and engagement mechanism; restraining relative movement of the first part and the second part on a helical path; transmitting torque from the first part to the second part on engagement of the engagement mechanism.
 12. A method according to claim 11, comprising the step of engaging the first part and second part by providing a first portion of a clutch on the first part and a second portion of the clutch on the second part.
 13. A method according to claim 11, including providing a throughbore in a portion of the first part and selectively moving a portion of the second part within the throughbore of the first part.
 14. A method according to claim 11, including suspending the first part from a wireline and allowing the second part to move under gravity relative to the first part.
 15. A method according to claim 14, including preventing axial movement beyond a first position of the second part relative to the first part.
 16. A method according to claim 15, including releasing the wireline suspension thereby allowing the first part to move axially relative to the second part.
 17. A method according to claim 11, including providing linear displacement device in the first part and axially aligning the linear displacement device with the second part.
 18. A method according to claim 17, including moving the linear displacement device in an axial direction to jar the second part. 